Refrigeration fan control system

ABSTRACT

A control for a refrigeration system including a compressor, a condensor, an evaporator and an electrically energized fan for passing air in heat exchange relation with respect to the compressor, the control including a light source, fan control means responsive to the light source for varying the operating speed of the fan, and means for varying the magnitude of light transmitted to the fan control means from the light source in response to the refrigerant pressure in the refrigeration system.

United States Patent 1191 Hoenisch Y 11] 3,811,292 [45] May 21, 1974REFRIGERATION FAN CONTROL SYSTEM [75] Inventor: Walter Harold Hoenisch,Albert Lea, Minn. [73] Assignee: King-Seeley Thermos Co., Ann

Arbor, Mich. [22] Filed:' Apr. 9, 1913 211 App]. 110.; 349,023

3,402,565 9/1968 Maynard 62/183 3,613,391 10/1971 Harter 62/1832,952,991

9/1960 St. Pierre 62/184 Primary Examiner-William J. Wye Attorney,Agent, ar'Fi'rm-l-laniess, Dickey & Pierce ABSTRACT A control for arefrigeration system including a compressor, a condensor, an evaporatorand an electrically energized fan for passing air in heat exchangerelation with respect to the compressor, the control including a lightsource, fan control means responsive to the light source for varying theoperating speed of the fan, and means for varying the magnitude of lighttransmitted to the fan control means from the light source in responseto the refrigerant pressure in the I refrigeration system.

' 20 Claims, 4 Drawing Figures PAiENTEUIAY 21 um I sum 2 or 2REFRIGERATION FAN CONTROL SYSTEM BACKGROUND OF THE INVENTION Inrefrigeration systems employing a refrigerant compressor, it isdesirable to obtain the maximum desired operating head pressure of thecompressor as soon as possible after the system is energized and tomaintain this head pressure throughout the freezing cycle. In air cooledcondensing units, especially under low ambient temperature operatingconditions, it is possible that the desired head pressure may never beobtained unless some provision is made to control the condensor fanspeed. As will be appreciated by those skilled in the art, theheadpressure in such refrigeration systems is directly proportional to therefrigerant discharge temperature, and accordingly, it has been proposedto utilize a pressure switch which delays energization of the com-'pressor fan until the proper compressor head pressure is obtained;however, this results in erratic operation of the fan from full on tooff and further results in large fluctuations in the head pressure.Additionally, such pressure switches result in the compressor fanoperating at full r.p.m. when such full operating speed is not required.Alternatively, it has been proposed to utilize an electronic phasecontrol device for operating the compressor fan. Such controls obtainthe desired. fan speed by an external variable resistor. In some suchsystems, a thermister is used to vary the resistance to the phasecontrol, although this approach has been found to be objectionable dueto the slow response to changes in compressor head pressure due to theinsuffi cient conductance of temperature changes to the thermister. Thisresults in high peaks in the compressor head pressure at the initiationof a freezing cycle, with an additional disadvantage being that thethermister senses high ambient temperatures which cause the compressorfan to operate too fast on start-ups.

Another approach to obtaining maximum operating head pressure ofrefrigerator compressors is to use a pressure bellows to operate apotentiometer that gives improved control of the fan through the phasecontrol. Disadvantages of the use of such bellows reside in the factthat they frequently involve cumbersome and costly operating mechanismsthat require critical adjustments due to the short travel of thepressure bellows operating the associated potentiometers.

in accordance with the principles of the present invention, a new andimproved fan control is provided.

which overcomes the various objectionable characteristics of similartype devices heretofore proposed in the prior art. The fan control ofthepresent invention utilizes a light source that may be in the form of asmall neon lamp and which is cooperative with aphotoelectric celllocated in theelectrical circuitry of the compressor fan motor. The celloperates to provide-a variable resistance which increases or decreaseswith the amount of light supplied by the neon lamp that is transmittedto the cell. For "example, when a maximum amount of light is transmittedto the cell, the resistance provided thereby may be quite low. forexample, in the order of 600-1000 ohms, whereas when the magnitude ofthe light is predeterminately decreased. the resistance provided bythecell may be in the order of 100.000 ohms. The method of varying themagnitude of the light transmitted from the neon lamp to the photoelectric cell, and thus changing the resistance through the cell inrelation to the discharge pressure of the refrigerator compressor, isaccomplished by interposing a light masking element between the lightsource and the photoelectric cell. More particularly, the light maskingelement is mounted on the shaft of a Bourdon tube that is connected tothe discharge end of the compressor, with the result that as thepressure increases, the light masking element is moved in a predeof therefrigeration system be in the order of 150 psi.

Accordingly, under low ambient temperature operating conditions, thefancontrol maintains the fan motor deenergized until the head pressurehas increased to approximately psi. At this point, the fan will operateat a very slow speed and the operating speed will gradually increase asthe head pressure increases. At approximately l50 psi, the controloperates the fan at full rpm. and this operating condition willcontinue'until the head pressure begins to drop, at which time the fanspeed will decrease accordingly.-

SUMMARY OF THE INVENTION This invention relates generally torefrigeration systems, and more particularly, to a new and improvedcontrol for operating the condensor fan in a manner so as to obtainpredetermined headpressure in the compressor. v

It is accordingly a general object of the present invention to provide anew and improved fan control for refrigeration compressors. i

It is a more particular object of the present invention .to provide anew and improved fan control of the above-described character whichincludes a light source and a photoelectric element for varying theresistance supplied to the fan motor, and which further includes meansfor selectively controlling the magnitude of the light transmitted fromthe light source to the photoelectric cell in accordance with thedischarge pressure of the compressor.

it is another object of the present invention to provide a new andimproved fan control of the abovedescribed type wherein the means forvarying the magnitude of the lightsupplied to the photoelectric cellcomprises a light masking element which is cooperable with a pressureresponsive Bourdon tube.

It is still another object of thepresent invention to provide a new andimproved fan control for use'in refrigeration systems of thetype whichcan be'used in ice making equipment.

It is yet another object of the present invention to provide a new-andimproved fan control of the abovedescribed type which is of a relativelysimple construction, is economical to manufacture and which will have along and effective operational life. v

Other objects and advantages of the present invention will becomeapparent from the following detailed description taken in conjunctionwith the accompanying drawings. I

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF A PREFERRED EMBODIMENTReferring in detail now to the drawings and in particular to FIG.lthereof, a refrigeration system is representatively illustrated ascomprising a conventional compressor 12, c'ondensor l4 and evaporator16. As is customary in the art, the compressor 12 is provided with acooling fan, generally designated by the numeral 18, which functions toselectively pass cooling air over the compressor during operationthereof. The fan 18 isshown as comprising an electrically energizedmotor 20, the operation of which is controlled by a 'fan control,generally designated by the numeral 22 and constructed inaccordance'with the principles of the present invention. Generallyspeaking, the fan control 22 is I connected to the refrigeration systemby means of a conduit 24 which is communicablewith the discharge side ofthe compressor 12, and by means of electrical conductors 26, 28 .whichsupply electrical energy to the fan motor 20. As will hereinafter bedescribed in detail, the discharge pressure of the compressor 12increases with the ambient temperature of the refrigeration system l0,and when the system 10 is operatingunde'r'low ambient temperatureconditions, such as below 70F.,

the discharge pressure of the compressor 12 is too low for efficientoperation. The proper compressor head pressure is particularly importantwhen the refrigeration system 10 is operatively associated with icemaking machines. especially where the refrigerant gases are utilized toheat the defrost water that is employed during the harvest cycle'of anice making machine. Normally, in such ice making machines, .a headpressure of approximately 'l5 0'psi is desirable. In high ambienttemperature conditions, the pressurcmay increase in excess of 200 psi;however, in low ambients, the fan control 22 of thev present inventionwill function to delay operation of the fan 18 until the head pressure.

has increased to approximately l00 psi. At this vpoint, the fan 18 willoperate-at a very slow r.p.m. and gradually increasein speedas the headpressure of the compressor increases. At approximately I50 psi, the fancontrol'22 operates the fan at full r.p.m. and-the fan 18 2 willcontinue to so operate until such time as the head pressure of thecompressor l2 begins to decrease, at

which time the fan speed'will decrease proportionately to reduce theheadpressure.

Referring now in detail to the construction of the fan a pair ofmounting flanges 34 and 36 on the opposite ends thereof which aresecured to the side 32 by means of suitable screws, bolts or the like38. The flanges 34, 36 are adapted to cooperate with the remainingportion of the housing (not shown) in operatively securing the side 32thereto, as will be appreciated by those skilled in the art. Themounting flange 46 is formed with an aperture 40 within which a suitablegrommet or the like 42 is provided, whereby to permit suitableelectrical conductors to pass from the exterior of the hous-' ing 30 tothe interior thereof, as is well known in the art. Generally speaking,the interior of the housing 30 contains a pressure sensing assembly 44,a phase control 46 and electrical terminal block 48, all of whichcomponents will hereinafter be described in detail.

Referring now in detail to the construction and operation of thepressure sensing assembly 44, the assembly 44 comprises a Bourdon tube,generally designated by the numeral 50, which is of a conventional,generally C-shaped configuration and is fabricated of a flattenedsuitable manifold block 52 which is communicable-via control 22 of thepresentinvention, as best seen in FIGS. 2-4, the fan control 22 iscontained or enclosed within a generally rectangular-shaped housing 30,one side 32 of which is depicted in the drawings. The interiorof thehousing 32 is preferably of a dark color to avoid any light reflections,as. will hereinafter be appreciated. The side 32 of the housing 30 isprovided with asuitable fluid fitting 53 with the conduit 24 thatcomrnunicates with the discharge side of the compressor 12, aspreviously mentioned. The end of the Bourdon tube oppositethat which issecured to the manifold block 52 is connected via a suitable mechanicallinkages 54 with a segmental, gear56 which is meshingly engagedwith-external teeth formed on a rotatable shaft 58. The mechanicallinkages 54 and gear segment 56 operate such that upon an increase inpressure within the Bourdon tube 50 due to an increase'in pressure onthe discharge side of the compressor 12, the shaft 58 will be'caused torotate, for purposes to be hereinafter described. As shown in FIG. 4,theouterendof the shaft 58 is journal supported by suitable bearingmeans 60 operatively secured within a support plate or the like 62attached to the inner side of the manifold block 52.

Disposed interiorly of the Bourdon tube 50 is a light source, generallydesignated by the numeral 64. The light source 64 preferably is in theform of a neon light 6.6 and is operatively mounted within a suitablesupport bracket 68 attached by suitable screws, bolts or the like 70 tothe side'32 of the housing 30. The neon light 66 is connectedviarsuitable electrical conductors 72, 74 with terminals 76 and 78 ofthe aforementioned terminal block 48, with suitable resistor means (notshown), such as a I200 ohm resistoror the like, being provided in theelectrical circuit to the .neon light 66 so that the samemay operate ona 1 15 volt source of electrical en- The light source 64 is cooperablewith a light sensitive photoelectric device, herein referred to as aphotoelectric cell and generally designated by the numeral 82. Thephotoelectric cell 82 may be of any one of a numberof different types ofconstructions and may light transmitted thereto. Preferably thephotoelectric cell 82 embodied in the present invention consists of acadmium sulphide cell of a construction well known in the art. Due tothe sensitivity of the photoelectric cell 82, it is preferable tomaintain the interior of the housing 30 shielded from exterior lightsources, as previously mentioned. The photoelectric cell 82 is operatively supported in a suitable carrier element, generally designated bythe numeral 84, which is located adjacent and above the end of the shaft58 which is rotatable by the Bourdon tube .50. The carrier element 84 isthreadably mounted on a generally externally threaded shaft or screwelement 86 which is in turn journal supported within a suitable internalbore formed in a mounting block 88 that is operatively secured to theside 32 of the housing 30'. The upper end of the shaft 86 is formed witha screwdriver receiving slot 90 by which the shaft 86 may be rotated,with the result that the carrier element 84 and photoelectric cell 82mounted thereon will move toward and away from the axis of the shaft 58and hence toward and away from a position generally in alignedconfronting relation with respect to the light source 64. Thus, thecontrol 22 may be adjusted in accordance with the desired head pressurein the associated refrigeration system. One side of the carrier element84 is formed with an elongated slot 92 which is adaptedto be slidablyengaged with an elongated guide member 94 having an upper, generallyloop-shaped portion 96 that is adapted to be secured to the side 32 bymeans of a suitable screw, bolt or the like 98. As will be appreciatedbythose skilled in the art, the interen'gagement of the slot 92 with theguide member 94 prevents rotation of the element 84 and photoelectriccell 82 upon upward and downward-movement thereof upon rotationaladjustment of the shaft 86. The photoelectric cell 82 is mounted on thecarrier 84 such that the light sensitive side thereof faces the lightsource 64, and the cell 82 is connected to the electric circuitry of thefan control 22 of the present invention by means ofa pair of electricalconductors 100 and 102 which are respectively connected to terminals 104and 106 of the terminal block 48.

the internal pressure within the Bourdon tube 50 is relatively low, forexample, in the order of approximately 150 psi, the aperture 114 is incomplete registry with the line of light transmission from the lightsource 64 to the photoelectric cell 82. In this condition, the maximumamount of light is transmitted to the photoelectric cell 82 whichresults in a minimum or zero resistance being interjected thereby intothe fan control circuit. As the pressure within the Bourdon tube 50decreases, for example, to approximately 125 psi, resulting in apredetermined amount of rotation of the element 108, the configurationof the control aperture 114 therein is such that approximately 25percent of the light transmission from the light source 64 to thephotoelectric cell 82 is blocked. Similarly, when the pressure withinthe Bourdon tube 50 drops still further, for example, to

' approximately 70 psi, the shape of the control aperture lri accordancewith the present invention,.interposed between the-photoelectric cell 82and the light source 64 isa light masking element, generally designatedby the numeral 108. The element 108 consists ofa generally disc-shapedmember which may be fabricated of a light impervious material, such asmetal or the like. The masking element 108 isformed with a centralopening 110 which is provided with a suitable mounting hub or the like112 adapted to operatively secure the element 108 on the end of theshaft 58. With this arrangement, upon rotation of the shaft 58 due to apressure change within the Bourdon tube 50, the masking element 108 willrotate about the axis of the shaft 58. The radial di-- mension of themasking element 108 is such that the element is adapted to interrupt orblock the transmission of light from the light source 64 to thephotoelectric cell 82; however, the element 108 is formed with a controlaperture, generally designated by the numeral 114, which is of apreselected configuration such that when the element 108 is selectivelyrotationally positioned, a predetermined magnitude of light will betransmitted from the'light source 64 throughthe aperture 114 to thephotoelectric cell 82. The shape oi" con 114 is such that approximatelyone-half the light from the light source 64 to the photoelectric cell 82isblocked; Finally, the control aperture 1141s such that when thepressure within the Bourdon tube 50 drops to some predetermined minimumlevel, approaching zero psi, the aperture 114 will be moved entirely outof registry with the photoelectric cell 82 and light source 64, with theresult that the masking element 108 entirely blocks the transmission oflight therebetween. It will be noted that the present invention is notintendedto be limited to the specific construction of the maskingelement 108 hereinbefore described, since the element 108 'may assumevarious other shapes and maybe fabricated of various other materials.For example, the eletransmission therebetween is blocked, and as theclear.

portion of the disc moves into registry with thelight source 64 due torotation of the shaft 58, a-selectively greater amount of light will betransmitted to the photoelectric cell 82, thereby achieving theabovedescribed results. it will also be n'oted that the particularconfiguration and location of the various components of the fan control22 of the present invention are not necessarily limited to thearrangement shown in the drawing and. that such components could bemounted on a conventional printed circuit board having the variouselectrical conductors described herein .printed thereon, as will beappreciatedby those skilled in the art. Additionally, it will be seenthat various means other than the adjustable shaft 86 may be providedfor varying the magnitude of light transmitted to the cell 82 for agiven desired head pressure. For example, instead of having thephotoelectric cell 82 bemovable by means of the aforedescribed shaft 86,it would be possible to have the masking element 108 adjustably mountedupon the shaft 58, whereby the element 108 could be selectivelyrotatably positioned upon the shaft I 58 in accordance with the desiredpressure of the comfiguration of the control aperture 114 is such thatwhen I pressor l2.

The fan motor 20 of the fan '18 consists of a typical triacs, etc. As iswell known in the art, the firing angle at which the control devices arecaused to conduct may be controlled by the input circuit to the gateelectrode of the control devices, thus varying the amount of energy fedto the fan motor 20. The phase control 36 and resistance profided by thecell 82 generally functions to control the input circuit of such acontrol device. More particularly, the phase control 36 is shown asbeing housed in a suitable enclosure 'or housing 118 which is secured tothe side 32 of the housing 30 by means of suitable screws,-bolts or thelike 120. The phase control may consist of any suitable known motorspeed control which generally functions to rapidly switch off" and onthe AC supply to the fan motor 20 by cutting off a fraction of the ACcycle. This, of course, is accomplished by controlling the phase angleof the AC wave at which the triac orother control rectifier istriggered. A suitable phase control is marketed by Omnetics Incorporatedof Syracuse, New York, and is marketed under the trade name Omnephase.Suitable AC phase control models sold under the Omnephase trade name aremodels 602A and 1002A and typically have an input voltage characteristicof I20 volts, an off state voltage of 200 volts, a forward voltage dropof reasons; anon state current of 6-10 amps, a peak surgeon-statecurrent of 100-200, and a peak off'st at e cfirr'nrdf 2 milliamperes. Itwill be appreciated, of

course; that various alternative AC phase controls may be utilizedwithout departing from the scope of the present invention and that theaforesaid typical phase control devices are described merely byway ofexample. The phase control 46 is communicable with the which, forexample, may consist of the electrical energy supplied to the compressor12.

Assuming'that the photoelectric cell 82 is properly positioned withrespect to the light source 64 and that V the light masking element 108-is properly rotationally positioned upon the shaft 58, so as to achievethe desired rotation thereof for agiven desirable range of pressurechanges occurring within'the Bourdon tube 50 and originating atthe-discharge side of the compressor 12. the operation of the fancontrol 22 of the present invention is such that when a minimum pressurecondition exists within the compressor 12, the masking element 108 isrotationally positioned so as to prevent the transmission of light fromthe light source 64 to the photoelectric cell 82. Accordingly, themaximum amount of electrical resistance is introduced into theelectrical circuit of the fan motor 20. Depending upon the particulartype of photoelectric cell 82 which is utilized, this resistance may bein the order of 100,000 ohms or greater. As the pressure at thedischarge end of the compressor 12 increases, the masking element 108will be rotated, thereby causing a greater amount of light to betransmitted from the light source 64 to the photoelectric cell 82.-Forexample, when the pressure in the Bourdo'n tube. 50 reachesapproximately 75 psi, approximately one-half of the light produced bythe continue to increase with increased pressure in the Bourdon tube 50until such time as the pressure therewithin is in the order of 150 psi,at which time virtually the entire amount of light produced by the lightsource 64 will be transmitted to the photoelectric cell 82. When themaximum amount of light is received by the photoelectric cell 82, theresistance introduced thereby is at a relatively low level, for example,in the order of 600 ohms or less, with the result that the fan motor 20is operatingat virtually full r.p.m., thereby resultingin the maximumamount of air being passed over the compressor l2.

As previously mentioned, the fan control 22 of the present inventionwill find particularly useful application in low ambient temperatureoperating conditions, particularly where the refrigeration system 10 isutilized in an ice making machine or the like wherein the electricalcircuitry of the fan control 22 of the present t defrost water is heatedby the discharge gases of the refrigeration system. it will beappreciated, of course, that the principles of the present inventionwill find wide and varied application other than ice making equipment,where a small, compact, easily adjustable fan control is to be employed.7

While it will be apparent that the preferred embodiment hereinillustratedis wellcalculated to fulfill the objects stated abovefit willbeappreciated that; the present invention is susceptible tomodification, variation, and change without departing'from the scope-ofthe invention. r

I claim: s i

l. A control for a refrigeration system including a compressor, acondensor, an evaporator and an electrically energized fan for passingair in heat exchange relation to the compressor,

said control including a light -source,= fan control means responsive tosaid light source produced for varying the operating speed and means forcontrolling the magnitude of light trans! mitted to the fan controlmeans from said light source in response to the said system.

2'. The invention as set forth in claim 1 which includes a Bourdontube'operable in response to the re-- frigerant pressure in thecompressor portion of said refrigeration system, which includes aphotoelectric cell,

.wherein said means for controlling the magnitude of light transmittedfrom said light source comprises a light masking element movable inresponse to operation'of said Bourdon tube.

3. The invention as set forth in claim 2 wherein said masking element isrotatable about a predetermined axis in response to operation of saidBourdon tube to control the magnitude of light transmitted from saidlight source to said photoelectric cell.

4. The invention as set forth in claim 3 which includes an electronicphase control, and wherein said photoelectric cell is cooperable withsaid phase control to control the firing angle .at which the phasecontrol supplies electrical energy to the cooling fan.

5. The invention as set forth in claim 3 wherein said I maskingelementis of a generally disc-shaped configuof the fan,

refrigerant pressure inration and has means thereon which is selectivelyinterposable between said light'source and said photoelectric cell forvarying the magnitude of light transmitted therebetween upon rotation ofsaid element.

6. The invention as set forth in claim 5 wherein said masking element ismounted on a rotatable shaft, and which includes mechanical linkagemeans actuable in response to operation of said Bourdon tube to rotatesaid shaft and said masking element thereon.

7. The invention as set forth in claim 6 which includes adjustment meansfor selectively varying the amount of light received by saidphotoelectric cell from said light source for a given pressure conditionin said refrigeration system.

8. The invention as set forth in claim 7 wherein said adjustment meanscomprise means for movably supporting said photoelectric cell relativeto said light source.

9. The invention as set forth in claim 1 wherein said control comprisesa housing having a low light reflective interior, which includes aBourdon tube and conduit means communicating said tube with thedischarge side of the refrigeration compressor, wherein said lightsource is located adjacent said-Bourdon tube, which includes a generallycircular shaped light masking element mounted for rotation about an axisarrangement generally coaxial of said Bourdon tube, which includesmechanical linkage means operatively connecting said Bourdon tube withsaid shaft, whereupon a change in pressure in said Bourdon tube resultsin rotation of said shaft, which includes a photoelectric cell disposedon the opposite side of said masking element from said light source,which further includes means on said masking element for varying themagnitude of the light transmitted to said photoelectric cell inresponse to changes in the rotational position of said masking element,and whereupon said refrigeration fan includes an AC motor whose speed iscontrolled by a control device, the firing angle of which is varied bythe resistance of the input circuit of the gate electrode of the controldevice, and wherein said photoelectric cell is operable to change theresistance in said input circuit and thereby vary the amount of energysupplied from a suitable source thereof to said fan motor.

10. A fan control to be used with an electrically energized cooling fanfor a refrigeration system, comprising.

a light source, v I an electrical circuit for supplying electricalenergy to said fan and including light sensitive variable-resistancemeans,

means for controlling the magnitude of light transmitted from saidsource to said light sensitive means. and

means for operating said last-mentionedmeans in response to therefrigerant pressure in said system.

-ll. The invention as set forth in claim 10 wherein f refrigerationsystem.

12. The invention as set forth in claim 11 which includes a Bourdon tubeoperable in response to the re- 10' frigerant pressure in the compressorportion of said refrigeration system, and wherein said light sensitivemeans comprises a photoelectric cell.

13. The invention as set forth in claim l2 wherein said means forcontrolling the magnitude of light transmitted from said source to saidlight sensitive means comprises a light masking element movable inresponse to operation of said Bourdon tube.

14. The invention as set forth in claim 13 wherein said masking elementis rotatable about a predetermined axis in response to operation of saidBourdon tube to control the magnitude of light transmitted from saidlight source to said photoelectric cell.

15. The invention as set forth in claim 14 which includes an electronicphase control, and wherein said photoelectric cell is in cooperationwith said phase control to control the firing angle at which the phasecontrol supplies electrical energy to the cooling fan.

16. The invention as set forth in claim 14 wherein said masking elementis of a generally disc-shaped configuration and has means thereon whichis selectively interposable between said light source and saidphotoelectric cell for varying the magnitude of light transmittedtherebetween upon rotation of said element.

17. The invention as set forth in claim 16 wherein said masking elementis mounted on a rotatable shaft, and which includes mechanical linkagemeans actuable in response to operation of said Bourdon tube to rotatesaid shaft and said masking element thereon. I

- 18. The invention as set forth in claim 17 which includes adjustmentmeans for selectively varying the amount oflight received by saidphotoelectric cell from said light source for a given pressure conditionin said refrigeration system. i

19. The invention as set forth in claim 18 wherein said adjustment meanscomprise means for movably supporting said photoelectric cell relativeto said light source.

20. The invention as set forth in claim 11 wherein said controlcomprises a housing having a low light refle'ctive interior, whichincludes a Bourdon tube and conduit means communicating said tube withthe discharge side of the refrigeration compressor, wherein said lightsource is located adjacent said Bourdon tube, which includes a generallycircular shaped light masking element mounted for rotation about an axisarrangernent generally coaxial of said Bourdon tube, which includesmechanical linkage means operatively connecting said Bourdon tube withsaid shaft, whereupon a change in pressure in said Bourdon tube resultsin rotation of said shaft, which includes aphotoelectric cell disposedon the opposite side of said masking element from said light source,which further includes means on said masking element for varying themagnitude of the light transmitted to said photoelectric cell inresponse to changes in the rotational posit-ion of said masking element,and whereupon said refrigeration fan includes an AC motor whose speed iscontrolled by a control device, the firing angle of which is varied bythe resistance of the input circuit of the gate electrode of the controldevice, and wherein said photoelectric cell is operable to change theresistance in said input circuit and thereby vary the amount of energysupplied from a suitable source thereof to said fan motor.

' UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 1,Dated May 21, 1974 Inventoflx) Walter Harold Hoenisch It is certifiedthat error appears in the'above-ideutified patent and that said LettersPatent are hereby corrected as shown below:

Column 1, line 18, delete "com"; line 19, "pressor" should be--condenser--; line 27, "compressor" should be -cor1denser--; line 38,"compressor" should be --condenser-; line 55, delete "com-"; line 56,"pressor"'should be "condenser-n Column 2, line 36, "compressors" shouldbe --c0ndensers-7-. Column 3, line 20, "compressor 12" should be"condenser 14"; line 22, 'd-el1ete "over"; llne 23, delete "thecompressor" and ip'sert therefor -'-thereover- -r-.

T "columns, line 39, "compressor" should be "condenser"; 7 Q

' Signed and; sealed this 7th day of January 1975.

(SEAL) Attest: McCOY M. GIBSON. JR. c. MARSHALL DANN' Attesting Offleer. Commissioner of Patents FORM PC4050 (10-69) UlcoMM-Dc cove- 69u.s. aoyuupmq rimrlus omc: you maps-an

1. A control for a refrigeration system including a compressor, acondensor, an evaporator and an electrically energized fan for passingair in heat exchange relation to the compressor, said control includinga light source, fan control means responsive to said light sourceproduced for varying the operating speed of the fan, and means forcontrolling the magnitude of light transmitted to the fan control meansfrom said light source in response to the refrigerant pressure in saidsystem.
 2. The invention as set forth in claim 1 which includes aBourdon tube opErable in response to the refrigerant pressure in thecompressor portion of said refrigeration system, which includes aphotoelectric cell, wherein said means for controlling the magnitude oflight transmitted from said light source comprises a light maskingelement movable in response to operation of said Bourdon tube.
 3. Theinvention as set forth in claim 2 wherein said masking element isrotatable about a predetermined axis in response to operation of saidBourdon tube to control the magnitude of light transmitted from saidlight source to said photoelectric cell.
 4. The invention as set forthin claim 3 which includes an electronic phase control, and wherein saidphotoelectric cell is cooperable with said phase control to control thefiring angle at which the phase control supplies electrical energy tothe cooling fan.
 5. The invention as set forth in claim 3 wherein saidmasking element is of a generally disc-shaped configuration and hasmeans thereon which is selectively interposable between said lightsource and said photoelectric cell for varying the magnitude of lighttransmitted therebetween upon rotation of said element.
 6. The inventionas set forth in claim 5 wherein said masking element is mounted on arotatable shaft, and which includes mechanical linkage means actuable inresponse to operation of said Bourdon tube to rotate said shaft and saidmasking element thereon.
 7. The invention as set forth in claim 6 whichincludes adjustment means for selectively varying the amount of lightreceived by said photoelectric cell from said light source for a givenpressure condition in said refrigeration system.
 8. The invention as setforth in claim 7 wherein said adjustment means comprise means formovably supporting said photoelectric cell relative to said lightsource.
 9. The invention as set forth in claim 1 wherein said controlcomprises a housing having a low light reflective interior, whichincludes a Bourdon tube and conduit means communicating said tube withthe discharge side of the refrigeration compressor, wherein said lightsource is located adjacent said Bourdon tube, which includes a generallycircular shaped light masking element mounted for rotation about an axisarrangement generally coaxial of said Bourdon tube, which includesmechanical linkage means operatively connecting said Bourdon tube withsaid shaft, whereupon a change in pressure in said Bourdon tube resultsin rotation of said shaft, which includes a photoelectric cell disposedon the opposite side of said masking element from said light source,which further includes means on said masking element for varying themagnitude of the light transmitted to said photoelectric cell inresponse to changes in the rotational position of said masking element,and whereupon said refrigeration fan includes an AC motor whose speed iscontrolled by a control device, the firing angle of which is varied bythe resistance of the input circuit of the gate electrode of the controldevice, and wherein said photoelectric cell is operable to change theresistance in said input circuit and thereby vary the amount of energysupplied from a suitable source thereof to said fan motor.
 10. A fancontrol to be used with an electrically energized cooling fan for arefrigeration system, comprising, a light source, an electrical circuitfor supplying electrical energy to said fan and including lightsensitive variable resistance means, means for controlling the magnitudeof light transmitted from said source to said light sensitive means, andmeans for operating said last-mentioned means in response to therefrigerant pressure in said system.
 11. The invention as set forth inclaim 10 wherein said refrigeration system includes a compressor andwherein said means for controlling the magnitude of light from saidsource to said light sensitive means comprises a movable member movablein response to the refrigerant pressure in the compressor portion of therefrigeration system.
 12. The invention as set forth in claim 11 whichincludes a Bourdon tube operable in response to the refrigerant pressurein the compressor portion of said refrigeration system, and wherein saidlight sensitive means comprises a photoelectric cell.
 13. The inventionas set forth in claim 12 wherein said means for controlling themagnitude of light transmitted from said source to said light sensitivemeans comprises a light masking element movable in response to operationof said Bourdon tube.
 14. The invention as set forth in claim 13 whereinsaid masking element is rotatable about a predetermined axis in responseto operation of said Bourdon tube to control the magnitude of lighttransmitted from said light source to said photoelectric cell.
 15. Theinvention as set forth in claim 14 which includes an electronic phasecontrol, and wherein said photoelectric cell is in cooperation with saidphase control to control the firing angle at which the phase controlsupplies electrical energy to the cooling fan.
 16. The invention as setforth in claim 14 wherein said masking element is of a generallydisc-shaped configuration and has means thereon which is selectivelyinterposable between said light source and said photoelectric cell forvarying the magnitude of light transmitted therebetween upon rotation ofsaid element.
 17. The invention as set forth in claim 16 wherein saidmasking element is mounted on a rotatable shaft, and which includesmechanical linkage means actuable in response to operation of saidBourdon tube to rotate said shaft and said masking element thereon. 18.The invention as set forth in claim 17 which includes adjustment meansfor selectively varying the amount of light received by saidphotoelectric cell from said light source for a given pressure conditionin said refrigeration system.
 19. The invention as set forth in claim 18wherein said adjustment means comprise means for movably supporting saidphotoelectric cell relative to said light source.
 20. The invention asset forth in claim 11 wherein said control comprises a housing having alow light reflective interior, which includes a Bourdon tube and conduitmeans communicating said tube with the discharge side of therefrigeration compressor, wherein said light source is located adjacentsaid Bourdon tube, which includes a generally circular shaped lightmasking element mounted for rotation about an axis arrangement generallycoaxial of said Bourdon tube, which includes mechanical linkage meansoperatively connecting said Bourdon tube with said shaft, whereupon achange in pressure in said Bourdon tube results in rotation of saidshaft, which includes a photoelectric cell disposed on the opposite sideof said masking element from said light source, which further includesmeans on said masking element for varying the magnitude of the lighttransmitted to said photoelectric cell in response to changes in therotational position of said masking element, and whereupon saidrefrigeration fan includes an AC motor whose speed is controlled by acontrol device, the firing angle of which is varied by the resistance ofthe input circuit of the gate electrode of the control device, andwherein said photoelectric cell is operable to change the resistance insaid input circuit and thereby vary the amount of energy supplied from asuitable source thereof to said fan motor.